[fix bug 1067143] Missing ZTE Open C on german language Firefox OS page

New policy going forward is that all e-bay phone links will show up on both `/firefox/os` and `/firefox/os/devices`, as per [this comment in the bug](https://bugzilla.mozilla.org/show_bug.cgi?id=1067143#c4).
Get rid of `class="developer-only"` here as well?